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<a name="Small-IPA-passes"></a>
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<p>
Next: <a href="Regular-IPA-passes.html#Regular-IPA-passes" accesskey="n" rel="next">Regular IPA passes</a>, Up: <a href="IPA-passes.html#IPA-passes" accesskey="u" rel="up">IPA passes</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p>
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<a name="Small-IPA-passes-1"></a>
<h4 class="subsection">9.4.1 Small IPA passes</h4>
<a name="index-small-IPA-passes"></a>
<p>A small IPA pass is a pass derived from <code>simple_ipa_opt_pass</code>.
As described in <a href="IPA.html#IPA">IPA</a>, it does everything at once and 
defines only the <em>Execute</em> stage.  During this
stage it accesses and modifies the function bodies.
No <code>generate_summary</code>, <code>read_summary</code>, or <code>write_summary</code>
hooks are defined.
</p>
<ul>
<li> IPA free lang data

<p>This pass frees resources that are used by the front end but are
not needed once it is done.  It is located in <samp>tree.c</samp> and is described by
<code>pass_ipa_free_lang_data</code>.
</p>
</li><li> IPA function and variable visibility

<p>This is a local function pass handling visibilities of all symbols.  This
happens before LTO streaming, so <samp>-fwhole-program</samp> should be ignored
at this level.  It is located in <samp>ipa-visibility.c</samp> and is described by
<code>pass_ipa_function_and_variable_visibility</code>.
</p>
</li><li> IPA remove symbols

<p>This pass performs reachability analysis and reclaims all unreachable nodes.
It is located in <samp>passes.c</samp> and is described by
<code>pass_ipa_remove_symbols</code>.
</p>
</li><li> IPA OpenACC

<p>This is a pass group for OpenACC processing.  It is located in
<samp>tree-ssa-loop.c</samp> and is described by <code>pass_ipa_oacc</code>.
</p>
</li><li> IPA points-to analysis

<p>This is a tree-based points-to analysis pass. The idea behind this analyzer
is to generate set constraints from the program, then solve the resulting
constraints in order to generate the points-to sets.  It is located in 
<samp>tree-ssa-structalias.c</samp> and is described by <code>pass_ipa_pta</code>.
</p>
</li><li> IPA OpenACC kernels

<p>This is a pass group for processing OpenACC kernels regions.  It is a
subpass of the IPA OpenACC pass group that runs on offloaded functions
containing OpenACC kernels loops.  It is located in
<samp>tree-ssa-loop.c</samp> and is described by
<code>pass_ipa_oacc_kernels</code>.
</p>
</li><li> Target clone

<p>This is a pass for parsing functions with multiple target attributes.
It is located in <samp>multiple_target.c</samp> and is described by
<code>pass_target_clone</code>.
</p>
</li><li> IPA auto profile

<p>This pass uses AutoFDO profiling data to annotate the control flow graph.
It is located in <samp>auto-profile.c</samp> and is described by
<code>pass_ipa_auto_profile</code>.
</p>
</li><li> IPA tree profile

<p>This pass does profiling for all functions in the call graph. 
It calculates branch
probabilities and basic block execution counts. It is located
in <samp>tree-profile.c</samp> and is described by <code>pass_ipa_tree_profile</code>.
</p>
</li><li> IPA free function summary

<p>This pass is a small IPA pass when argument <code>small_p</code> is true.
It releases inline function summaries and call summaries.
It is located in <samp>ipa-fnsummary.c</samp> and is described by
<code>pass_ipa_free_free_fn_summary</code>.
</p>
</li><li> IPA increase alignment

<p>This pass increases the alignment of global arrays to improve
vectorization. It is located in <samp>tree-vectorizer.c</samp>
and is described by <code>pass_ipa_increase_alignment</code>.
</p>
</li><li> IPA transactional memory

<p>This pass is for transactional memory support.
It is located in <samp>trans-mem.c</samp> and is described by
<code>pass_ipa_tm</code>.
</p>
</li><li> IPA lower emulated TLS

<p>This pass lowers thread-local storage (TLS) operations
to emulation functions provided by libgcc.
It is located in <samp>tree-emutls.c</samp> and is described by
<code>pass_ipa_lower_emutls</code>.
</p>
</li></ul>

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